Radiofrequency identification (RFID) tags are well known in the art. RFID tags are small electronic circuits that respond with a data-carrying RF reply signal when interrogated with an RF signal at a particular frequency. Tags are either passive or active. Passive tags rely on the energy of the interrogation signal to generate the reply signal; active tags carry their own battery. Active tags have a much longer range than active tags. Active tags typically can be queried up to about 150 feet distant; passive tags typically can be queried up to about 10 or 20 feet distant. In recent years, the maximum range of both passive and active tags has been increased by technological advancements in the field.
RFID tags are expected to have a large number of applications in many settings to track and store materials and inventory. Libraries, hospitals, warehouses, retail stores, manufacturing plants, military bases, and the like are all expected to employ RFID tags for various applications.
A problem with RFID tags is determining where the tag is located relative to the RFID reader device. The interrogating radio waves emitted by the RFID reader are of course invisible, and so provide no indication to the user where the reader is scanning. This can cause confusion for the user when there are many RFID tags present, or when the user wants to scan for tags in a localized area, or when the user wants to identify a particular RFID tag among many.
Some RFID reader devices can electronically determine the location of an RFID tag. Typically, this is accomplished by triangulation, using the data generated from a plurality of networked RFID readers in different locations. A problem with electronic RFID tag location is that, even though the tag location may be known electronically, there is no way to indicate to the user the location of the tag.
Hence, there is a need for an RFID reader that can indicate to the user where the RFID reader is scanning, or indicate to the user the tag location.